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Item 1.01 Entry into a Material Definitive Agreement

On October 7, 2011, Clean Diesel Technologies, Inc. (the “Company”) signed a purchase agreement with Lincoln Park Capital Fund, LLC (“LPC”), an Illinois limited liability company, together with a registration rights agreement, whereby LPC has agreed to purchase up to $10 million of the Company’s common stock over a 30-month period (the “Purchase Agreement” and “Registration Rights Agreement,” respectively). Under the Registration Rights Agreement, the Company agreed to file a registration statement related to the transaction with the U.S. Securities & Exchange Commission (“SEC”) covering the shares that have been issued or may be issued to LPC under the Purchase Agreement. After the SEC has declared effective the registration statement related to the transaction, the Company has the right, in its sole discretion, over a 30-month period to sell shares of its common stock to LPC in amounts of up to $500,000 to up to $1,500,000 per sale, depending on certain conditions as set forth in the Purchase Agreement, up to the aggregate amount of $10 million.

There are no upper limits to the price LPC may pay to purchase the Company’s common stock and the purchase price of the shares related to the $10 million of future funding will be based on the prevailing market prices of the Company’s shares preceding the time of sales as computed in accordance with the Purchase Agreement without any fixed discount, with the Company controlling the timing and amount of future sales, if any, of shares to LPC.

LPC has covenanted not to cause or engage in any manner whatsoever, any direct or indirect short selling or hedging of the Company’s shares of common stock. In consideration for entering into the Purchase Agreement, the Company issued to LPC 40,247 shares of common stock as a commitment fee and is required to issue up to 80,494 shares of common stock pro rata as LPC purchases the $10 million of the Company’s common stock over the 30-month period. The Purchase Agreement may be terminated by the Company at any time at its discretion without any cost or penalty. The proceeds received by the Company under the Purchase Agreement are expected to be used for working capital and general corporate purposes.

The foregoing description of the Purchase Agreement and the Registration Rights Agreement are qualified in their entirety by reference to the full text of the Form of Purchase Agreement and the Form of Registration Rights Agreement, attached hereto as Exhibit 10.1 and 10.2, respectively, and each of which is incorporated herein in its entirety by reference.

Item 2.02 Results of Operations and Financial Condition

The information contained in this Item 2.02 and in the accompanying Exhibit 99.1 shall not be deemed filed for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or incorporated by reference in any filing under the Exchange Act or the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

On October 11, 2011, the Company announced via press release selected preliminary unaudited results for the three-month period ended September 30, 2011. A copy of the press release is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

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Item 3.02 Unregistered Sales of Equity Securities

The information contained above in Item 1.01 is hereby incorporated by reference into this Item 3.02.

Item 7.01 Regulation FD Disclosure

The information contained in this Item 7.01 and in the accompanying Exhibit 99.1 shall not be deemed filed for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or incorporated by reference in any filing under the Exchange Act or the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

The information set forth in “Item 2.02. Results of Operations and Financial Condition,” including the exhibit referred to therein, is incorporated herein by reference.

Item 9.01 Financial Statements and Exhibits

The information contained in the accompanying Exhibit 99.1 in this Item 9.01 and shall not be deemed filed for purposes of Section 18 of the Securities Exchange Act of 1934, as amended, or incorporated by reference in any filing under the Exchange Act or the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

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SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned hereunto duly authorized.

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